Method and system for inter-cell interference coordination in wireless networks

ABSTRACT

A method, system, and non-transitory computer-readable storage medium for managing inter-cell interference in a wireless network is provided. The method may be executed by at least one processor at a small cell gateway and may include receiving, uplink interference power corresponding to a first small cell base station (SCBS). The method may further include receiving neighboring cell information of the first SCBS, the neighboring cell information including information on a first plurality of SCBSs neighboring the first SCBS. The method may further include determining based on the received uplink interference power, that the first SCBS is experiencing inter-cell interference and determining a second plurality of SCBSs from among the first plurality of SCBSs that are interfering with the first SCBS. The method may further include adjusting uplink power allocation corresponding to a second SCBS from among the second plurality of SCBSs.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application is a continuation of and claims the benefit of priorityto U.S. patent application Ser. No. 14/172,381, filed Feb. 4, 2014(currently pending), which claims priority under 35 U.S.C. §119 toIndian Patent Application No. 493/CHE/2013, filed Feb. 5, 2013 in theIndian Patent Office. The entire disclosures of the above-referencedapplications are incorporated herein by reference.

TECHNICAL FIELD

The disclosure generally relates to wireless networks and, moreparticularly, to coordinating inter-cell interference in wirelessnetworks.

BACKGROUND

Rapid increases in the mobile subscriber base and the recent emergenceof new applications (e.g., MMOG (Multimedia Online Gaming), mobile TV,Web 2.0, high definition video streaming), combined with an increasinglevel of penetration of data-intensive devices (e.g., smart phones,broadband enabled laptops, tablets and other devices), has resulted inthe explosion of internet data traffic carried by mobile networks. Toincrease the capacity of a cellular network, small cell deployments arebeing investigated vigorously by industry and standardization bodies.

Generally, small cells (e.g., “nanocells” or “femtocells”) may bepersonal miniature base stations installed on the subscriber's premisesfor providing cellular services within a home or enterprise. In contrastwith a typical mobile macro cell which might have a range of up toseveral tens of kilometers, small cells may be low-powered radio accessnodes that operate in licensed and unlicensed spectrums with a range of,for example, between ten meters to several hundred meters. Typically,small cells may be connected to the Internet and the cellular operator'score network via a small cell gateway (“SC-GW”).

As an example, small cells are being implemented in wireless networksimplementing the 3GPP Long-Term Evolution (LTE) standards. In 3GPP LTEstandards, a small cell is termed as a Home eNodeB (HeNB) or small cellbase station (SCBS). Throughout this document, HeNB and SCBS are usedinterchangeably to refer generically to a small cell or small cell basestation. The HeNB is connected to the Evolved Packet Core (EPC) via theSC-GW.

Each SCBS may cater to multiple user equipments (UEs) or mobileterminals under its coverage area. UEs in a coverage area of one SCBS(e.g., within a given cell) may be subjected to interference from theUEs or mobile terminals from other SCBS coverage area or fromsurrounding macro base stations coverage area. As the number of UEs ormobile terminals increases, the magnitude of the interference may alsoincrease. This interference may affect the quality of service of theapplication packets sent from UEs or mobile terminals to the SCBS, orvice versa, due to packet corruption or packet drop.

According to a conventional technique that has attempted to address thisinterference problem between different cells, neighboring SCBSs exchangepower control and interference coordination messages with each other.Based on this message exchange, interference coordination takes place.However, such exchanging of interference coordination messages betweenSCBSs every time the resource allocation is done may be overwhelming forthe SCBS given that, in some instances, SCBSs may be embedded deviceswith low capacity and processing power.

SUMMARY

Accordingly, there exists a need for techniques for improved inter-cellinterference coordination in wireless networks such as LTE.

According to an exemplary embodiment, a method of managing inter-cellinterference in a wireless network is provided. The method may beexecuted by at least one processor at a small cell gateway and mayinclude receiving, by the at least one processor, uplink interferencepower corresponding to a first small cell base station (SCBS). Themethod may further include receiving, by the at least one processor,neighboring cell information of the first SCBS, the neighboring cellinformation including information on a first plurality of SCBSsneighboring the first SCBS. The method may further include determining,by the at least one processor, based on the received uplink interferencepower, that the first SCBS is experiencing inter-cell interference. Themethod may further include in response to determining that the firstSCBS is experiencing inter-cell interference, determining, by the atleast one processor, a second plurality of SCBSs from among the firstplurality of SCBSs that are interfering with the first SCBS. The methodmay further include adjusting, by the at least one processor, uplinkpower allocation corresponding to a second SCBS from among the secondplurality of SCBSs.

According to another exemplary embodiment, a non-transitorycomputer-readable storage medium is provided that stores instructionswhich when executed by at least one processor at a small cell gatewayenable the at least one processor to execute a method of managinginter-cell interference in a wireless network. The method may includereceiving, by the at least one processor, uplink interference powercorresponding to a first small cell base station. The method may furtherinclude receiving, by the at least one processor, neighboring cellinformation of the first SCBS, the neighboring cell informationincluding information on a first plurality of SCBSs neighboring thefirst SCBS. The method may further include determining, by the at leastone processor, based on the received uplink interference power, that thefirst SCBS is experiencing inter-cell interference. The method mayfurther include in response to determining that the first SCBS isexperiencing inter-cell interference, determining, by the at least oneprocessor, a second plurality of SCBSs from among the first plurality ofSCBSs that are interfering with the first SCBS. The method may furtherinclude adjusting, by the at least one processor, uplink powerallocation corresponding to a second SCBS from among the secondplurality of SCBSs.

According to another exemplary embodiment, a system for managinginter-cell interference in a wireless network is provided. The systemmay include at least one processor and a memory storing instructions forexecution by the at least one processor. The at least one processor maybe configured by the instructions to receive uplink interference powercorresponding to a first small cell base station. The at least oneprocessor may be further configured to receive neighboring cellinformation of the first SCBS, the neighboring cell informationincluding information on a first plurality of SCBSs neighboring thefirst SCBS. The at least one processor may be further configured todetermine based on the received uplink interference power, that thefirst SCBS is experiencing inter-cell interference. The at least oneprocessor may be further configured to, in response to determining thatthe first SCBS is experiencing inter-cell interference, determine asecond plurality of SCBSs from among the first plurality of SCBSs thatare interfering with the first SCBS. The at least one processor may befurther configured to adjust uplink power allocation corresponding to asecond SCBS from among the second plurality of SCBSs.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the disclosure, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of thepresent disclosure and together with the description, serve to explainthe principles of the disclosure.

FIG. 1 illustrates an exemplary network architecture for a broadbandwireless network.

FIG. 2 illustrates an exemplary architecture for an HeNB.

FIG. 3 illustrates an exemplary architecture for a small cell gateway.

FIG. 4A is a flow chart of an exemplary machine algorithm for inter-cellinterference coordination.

FIG. 4B is a continuation of the machine algorithm of FIG. 4A settingforth additional exemplary steps.

FIG. 4C is a further continuation of the machine algorithm of FIG. 4Asetting forth additional exemplary steps.

FIG. 4D is an even further continuation of the machine algorithm of FIG.4A setting forth additional exemplary steps.

FIG. 4E is an even further continuation of the machine algorithm of FIG.4A setting forth additional exemplary steps.

FIG. 4F is an even further continuation of the machine algorithm of FIG.4A setting forth additional exemplary steps.

FIG. 5 is an exemplary machine algorithm that is an overview of theinter-cell coordination process.

DETAILED DESCRIPTION

Exemplary embodiments of the present disclosure will be described withreference to the accompanying drawings. Wherever possible, the samereference numbers will be used throughout the drawings to refer to thesame or like parts. While exemplary embodiments are described herein,modifications, adaptations, and other implementations are possible,without departing from the spirit and scope of the invention.Accordingly, the following detailed description does not limit theinvention. Instead, the proper scope of the invention is defined by theappended claims.

An exemplary high level network depicting a broadband wireless networkarchitecture is illustrated in FIG. 1. For purposes of illustration, thenetwork of FIG. 1 corresponds to an LTE network. However, the depictedLTE network is merely an exemplary network, and thus it will beunderstood that the teachings of the disclosure contemplate otherbroadband wireless networks such as, for example, WiMax, High SpeedPacket Access (3GPP's HSPA), etc.

In FIG. 1, one or more of UE 14-1, 14-2, 14-3, through 14-m (each alsoreferred to as UE 14) may communicate wirelessly with one or more SCBSs11-1 through 11-n (each also referred to hereinafter as SCBS 11 or HeNB11). A UE may be any type of computing component that can communicatewith an SCBS 11. For example, a UE may be a cell phone, PDA, tabletcomputer, or other user device. One or more of HeNBs 11 may communicatethrough a small cell gateway 16 (hereinafter referred to as SC-GW 16) toan evolved packet core (EPC) 12 that may include a Mobility ManagementEntity (MME) 13. The functionalities of HeNB 11, SC-GW 16, EPC 12, andMME 13 are well known in the art and a detailed explanation thereof isomitted here for conciseness. Briefly, the functionalities of HeNB 11may include radio resource management header compression and encryptionof user data stream, packet scheduling and transmission, physical layerprocessing, etc. MME 13 may be responsible for non-access stratum,ciphering and integrity protection, intercore network signaling, SAE(system architecture evolution) bearer control, handover, etc. EPC 12may also include, among other things, a serving gateway (SGW) (notshown) and packet-data network gateway (PDN GW) (not shown).

In the network architecture of FIG. 1, depending on their location at agiven time, the coverage area of HeNB 11-1 may overlap with the coveragearea of one or more of HeNBs 11-2 through 11-n, resulting ininterference between the HeNBs. For example, UEs 14-1, 14-2, or 14-3 inthe coverage area of HeNB 11-1 may be subject to interference from UE14-m supported by HeNB 11-n. This interference may affect the quality ofservice of the application packets sent from the UEs to the respectiveHeNBs or vice versa.

To provide an improved inter-cell interference coordination mechanismthat does not place the entire burden of interference coordination onthe HeNB 11, an exemplary Interference Coordination Agent (ICA) 15 maybe provided in HeNB 11 and an exemplary Interference CoordinationManager (ICM) 17 may be provided in the SC-GW 16. While FIG. 1illustrates that the ICA 15 may be provided in HeNB 11 and ICM 17 may beprovided in SC-GW 16, ICA 15 and ICM 17 may be provided in otherlocations. For example, ICA 15 and ICM 17 may be provided in dedicatedunits separate from HeNB 11 and SC-GW 16, respectively. An exemplaryimplementation of the ICA 15 in HeNB 11 is illustrated in FIG. 2 and anexemplary implementation of the ICM 17 in SC-GW 16 is illustrated inFIG. 3. Detailed operations of the ICA 15 and ICM 17 are explained withreference to FIGS. 4A-4F.

As shown in FIG. 2, HeNB 11 may include, among other things, amanagement application 201, ICA 15, and call processing application 202.Each of these components may reside as code in memory or as dedicatedcircuitry on the same or different hardware processors in HeNB 11.Management application 201 may allow the operator or manager of HeNB 11to specify parameters for HeNB 11 used for radio resource management.ICA 15 may obtain and store context data for HeNB 11 such as a neighborrelation table, operating channel bandwidth information, uplinkinterference power, etc. For example, the operating channel bandwidthmay specify the physical resource blocks that constitute the uplinkchannel bandwidth for a given HeNB 11. A physical resource block may beformed, for example, of a group of 12 sub-carriers in LTE. Each of thesecontext data will be described in greater detail with reference to FIGS.4A-4F.

ICA 15 may transmit some or all of this context data to SC-GW 16 and,more particularly, to ICM 17 (explained in detail with reference toFIGS. 3 and 4A-4F). ICA 15 may receive an interference coordinationdecision from ICM 17 that may include resource allocation information(RAI) for HeNB 11. The RAI received from ICM 17 may indicate, forexample, an adjustment to the power allocation for one or more physicalresource blocks (PRBs) in a given HeNB 11's uplink system bandwidth. ICA15 may initiate an enforcement command to call processing application202 to enforce the interference coordination decision by ICM 17. Callprocessing application 202 may interface with UE 14 and execute theinterference coordination decision. Call processing application 201 mayalso report a status of execution of the interference coordination toICA 15, which may report the status to ICM 17.

FIG. 3 illustrates an exemplary configuration for the SC-GW 16. SC-GW 16may include management application 301 and ICM 17. Each of thesecomponents may reside as code in memory or as dedicated circuitry on thesame or different hardware processors in SC-GW 16. Managementapplication 301 may allow the operator or manager of SC-GW 16 to specifycertain parameters for SC-GW 16 that the ICM 17 may use to implement theinter-cell interference coordination process. For example, using thespecified parameters (which are discussed in further detail withreference to FIGS. 4A-4F), ICM 17 may determine one or more interferencecoordination groups, each of which may include a victim SCBS 11 (or HeNB11) that is interfered by one or more other interfering SCBSs 11. Foreach of the interference coordination groups, ICM 17 may determine oneor more adjustments that can be made in the power allocation and/orhopping sequence for the SCBSs 11 to minimize the interferenceexperienced by the victim SCBS 11.

FIGS. 4A-4F illustrate in detail an exemplary machine algorithmdescribing exemplary functionality of ICA 15 and ICM 17 consistent withthe disclosed embodiments. Certain steps in the machine algorithm may beexecuted by ICA 15 while others by ICM 17. The process is distributedover FIGS. 4A-4F where circles with roman numerals therein indicate thecontinuity between the different figures. To explain the functionalityof ICA 15 and ICM 17, consider the following scenario. Four SCBSs 11 orHeNBs 11 (B1, B2, B3, and B4) are connected to SC-GW 16. Suppose, theuplink bandwidth is as follows: B1=3 MHz; B2=1.4 MHz; B3=5 MHz; andB4=10 MHz.

In LTE, for example, the usable PRB indexes (each P(i) indicates onePRB) spanning the uplink bandwidth of the SCBSs 11 may be as follows:

i. B1=<P0, P1, . . . , P14>;

ii. B2=<P0, P1, . . . , P5>;

iii. B3=<P0, P1, . . . , P24>; and

iv. B4=<P0, P1, . . . , P49>;

In S401, ICM 17 may obtain one or more of the following parameters frommanagement application 301 that may be grouped into (1) interferencecoordination group configuration parameters and (2) interferencecoordination parameters. As explained in detail in the steps to follow,the interference coordination group configuration parameters may beutilized by ICM 17 to form one or more interference coordination groups(hereinafter referred to as “ICGs”), and the interference coordinationparameters may be utilized by ICM 17 to execute inter-cell coordinationbetween SCBSs in the ICGs.

Interference Coordination Group Configuration Parameters

Φ_(threshold)—threshold intensity of co-channel/adjacent channelinterference power threshold;

Δ_(threshold)—inter base station distance threshold; and

σ_(threshold)—cell radius threshold;

Interference Coordination Parameters

ψ_(threshold)—intensity of co-channel/adjacent channel interferencepower threshold per physical resource block (PRB);

γ_(threshold)—uplink power allocation threshold per PRB; and

τ_(periodicity)—periodicity of broadcasting resource allocationinformation (RAI) in the ICG.

As each of the four SCBSs 11 (B1, B2, B3, and B4) are registered atSC-GW 16, in S402, ICM 17 may obtain the radio channel supported by eachof the SCBS 11, the system bandwidth, and number of PRBs supported bythe four SCBSs 11. Accordingly, ICM 17 may obtain the exemplary PRBindex distribution for each of the SCBSs 11 set forth above.

In S403, each of the SCBSs 11 (B1, B2, B3, and B4) may transmit thefollowing information to ICM 17:

i. Neighbor relation Table (NRT);

ii. Uplink received Co-channel & Adjacent Channel interference powermeasured for the whole system bandwidth; and

iii. Minimum and Maximum RSRP (Reference Signal Received Power) valuesreported by the UEs attached to the SCBS 11;

iv. Average uplink power allocation over the uplink system bandwidth

The NRT (also referred to as “neighboring cell information”) mayindicate information as to who the neighboring SCBSs 11 are for a givenSCBS 11. For example, B1 may indicate that B2, B3, and B4 are itsneighbors. Hence, the NRT of B1 may be <B2, B3, B4>. B2 may indicate,for example, that its NRT includes <B1, B3, B4, B5> where B5 may be anSCBS 11 attached to another SC-GW 16 or the same SC-GW 16 as B1.

The uplink received co-channel & adjacent channel interference power(Φi) may indicate the uplink interference power experienced by an SCBS11 over its uplink system bandwidth. For example, B1 may indicate theuplink interference power experienced in each of its PRBs P0 thru P14.Hence, in FIG. 4B, K may be 14 for B1 and i may be 1 for B1.

The maximum and minimum RSRP values may correspond to the maximum andminimum values experienced by UEs connected to the SCBS 11. For example,if three UEs are connected to B1, then B1 may determine the RSRP valuesfor each of the three UEs and send the maximum and minimum values fromamong the three values.

The uplink power allocation (γ) may indicate the power allocated by eachof the SCBSs 11 for each of the PRBs. For example, γ for B1 may indicatethe average power allocated by B1 for each of its PRBs P0 thru P14. Itwill be noted that different SCBSs may allocate different uplink powerfor the same PRB index. For example, PRB index P0 is used by both SCBSsB1 and B3 but they may allocate different uplink power for P0.

Having received the above information from each of the SCBSs 11, ICM 17may compute the following parameters for each of the SCBSs 11:

i. Inter base station distance between an SCBS 11 and each of itsneighbors specified in the NRT. So, for example, ICM 17 may compute theinter base station distance (Δ) between B1 and B2, B1 and B3, B1 and B4as B2, B3, B4 are specified in the NRT for B1.

ii. Average uplink interference power experienced across the uplinksystem bandwidth. For example, for B1, ICM 17 may compute Φ₁ ^(avg) asthe average of the uplink interference powers across its PRBs P0 thruP14.

iii. Cell radius a for the SCBS 11 from the maximum and minimum RSRPvalues for the SCBS 11.

After determining the above information, ICM 17 may proceed to forminterference coordination groups (ICGs). For example, ICM 17 may cyclethrough each of SCBSs 11 (here, B1 through B4) and determine whether anyof the SCBSs 11 is a victim SCBS in that it is experiencing asignificant amount of interference from one or more of its neighbors(B2, B3, and B4). Having determined a victim SCBS 11, ICM 17 maydetermine the SCBSs 11 that are interfering with the victim SCBS 11. Thevictim SCBS 11 and the interfering SCBSs 11 may form one ICG. The aboveformation of an ICG is described with reference to S404 thru S410.

In S404, ICM 17 may begin executing a loop that goes through each SCBS11. N in S404 may be four in the exemplary scenario discussed herebecause SC-GW 16 is connected to four SCBSs. In S405, ICM 17 maydetermine whether the SCBS 11 selected in an iteration of S404 is avictim SCBS. ICM 17 may determine an SCBS 11 to be a victim SCBS if for,example, the average uplink interference power determined in S403 forthat SCBS is greater than a threshold value. For example, ICM 17 maydetermine that B1 is a victim SCBS if Φ₁ ^(avg) is greater thanΦthreshold. If ICM 17 determines that B1 is not a victim in S405, ICM 17may proceed back to S404 and select the next SCBS 11 (for example, B2).

If ICM determines that B1 is a victim SCBS, ICM 17 may create a new ICGand increment an ICG counter in S406. In S407, ICM 17 may add B1 (thevictim SCBS in this example) to the ICG and mark B1 as the victim.

Next, ICM 17 may identify all SCBSs that are interfering with B1. Forexample, ICM 17 may execute a loop in S408 that looks at each of B1'sneighbors specified in B1's neighboring cell information or NRT anddetermines in S409 whether both the following conditions are true forthe neighboring SCBS:

i. whether the inter base station distance between B1 and theneighboring SCBS is less than a threshold value (Δ_(threshold))specified by the operator

ii. whether the neighboring SCBS's cell radius is greater than athreshold value (σ_(threshold)) specified by the operator.

If both conditions are satisfied in S409, then in S410, ICM 17 may addthat neighboring SCBS 11 to the ICG for B1 (the victim SCBS here) andmark the neighboring SCBS 11 as an interferer. If the conditions are notsatisfied in S409, ICM 417 may repeat step 409 for the next neighboringSCBS until the conditions have been met for all neighboring SCBSs of B1.

Once the conditions have been met for all neighboring SCBSs of thevictim SCBS (here, B1), control may proceed back to S404 where ICM 17may now check whether the next SCBS (B2) is a victim. If B2 is a victim,a new ICG may be formed and the above steps repeated. The loop of S404may continue to repeat until all the SCBSs have been exhausted for SC-GW16.

Now assume that S404 thru S410 yield two ICGs. Assume that a first ICGhas victim SCBS as B1 with B2, B3, and B4 as the interferers. Alsoassume that a second ICG has victim SCBS as B4 with B2 and B3 asinterferers. Once the ICGs have been formed, ICM 17 may determine acommon resource pool (CRP) for each of the ICGs by executing S411 andS412. A common resource pool (CRP) for an ICG may be constituted by thePRBs that are common across all the SCBSs constituting the ICG. Forexample, for the first ICG in the example above, the CRP may include allPRBs that are common for B1, B2, B3, and B4. For the second ICG, the CRPmay include all PRBS that are common for B2, B3, and B4. For thefollowing system bandwidth,

i. B1=<P0, P1, . . . , P14>;

ii. B2=<P0, P1, . . . , P5>;

iii. B3=<P0, P1, . . . , P24>; and

iv. B4=<P0, P1, . . . , P49>,

the CRP for ICG(1) will be, for example, CRP(1)=<P0, P1, . . . , P5>

Having determined the ICGs, ICM 17 may determine how to executeinterference coordination for each of the ICGs. ICM 17 may execute afirst loop (S413) for each of the ICGs. In the first loop for an ICG,ICM 17 may execute a second loop (S414) for each constituent SCBS of theICG. In the second loop, ICM 17 may check whether the SCBS is aninterferer in S415. If the SCBS is determined to be an interferer inS415, a third loop (S416) may be executed for each of the PRBs in theCRP of the ICG. In the third loop, ICM 17 may check the following twoconditions in S417:

i. whether the uplink interference power experienced by the victim SCBSfor that PRB is greater than the threshold value (ψ_(threshold)) for theuplink interference power specified by the operator; and

ii. whether the uplink power allocated by the interfering SCBS for thatPRB is greater than the threshold value (γ_(threshold)) for uplink powerallocation per PRB specified by the operator.

If each of the two conditions is satisfied in S417, ICM 17 may reducethe uplink power allocation for that PRB of the interfering SCBS by somefactor and indicate this information in the RAI for the interferingSCBS.

The above description for steps 413 through 418 will become clear bytaking the following example. In S413, ICM 17 may enter the first loopfor ICG(1). In the second loop of S414 and S415, ICM 17 may determinethat B2 is an interferer for ICG(1). Hence, ICM 17 may execute the thirdloop for B2 for each of PRBs P0 thru P5 of ICG(1). For example, in S417,ICM 17 may check whether the uplink interference power experienced byvictim SCBS B1 in PRB P0 is greater than a corresponding threshold valueand whether the uplink power allocated by interferer B2 in PRB P0 isgreater than the corresponding threshold value. If the conditions aretrue in S417, then in S418, ICM 17 may reduce the uplink power allocatedby interferer B2 for PRB P0 and indicate this reduction in B2's RAI.Next, ICM 17 may execute S417 for the next PRB, P1 and so on. Once, allthe PRBs of the CRP(1) are exhausted, ICM 17 may execute S416-S418 forthe next interferer, B3.

In addition to adjusting the uplink power allocation of individual SCBSsin certain PRBs, ICM 17 may determine (S419), for each ICG, anon-overlapping set of PRBs from the corresponding CRP for eachconstituent SCBS of the ICG. For example, for CRP(1) corresponding toICG(1), the CRP includes 6 PRBs (P0 thru P5) and ICG (1) includes 4SCBSs (B1 thru B4). Therefore, in S419, four non-overlapping sets ofPRBs may be determined and assigned to each of the SCBSs in the ICG. Forexample, PRBs P0, P1, P2 may be assigned to B1, PRB P3 may be assignedto B2, PRB P4 may be assigned to B3, and PRB P5 may be assigned to B4.This assignment may be indicated in the RAI of each of the SCBSs. Itwill be understood that the above PRB allocation is only an example andany non-overlapping allocation may be assigned by ICM 17. Moreover, theallocation decision may be optimized by ICM 17 by using an optimizationalgorithm.

In S420, ICM 417 may send the RAIs to the respective SCBSs. The RAI maybe sent periodically at time interval τ_(periodicity). Additionally, thePRB assignment of S419 may be hopped at the same or different timeinterval. For example, after one time interval τ_(periodicity) the PRBassignment may be hopped: B1 may be assigned PRBs P3, P4, P5, B2 may beassigned PRB P0, B3 may be assigned PRB P1, and B4 may be assigned PRBP2.

At S421, each of the SCBSs 11 connected to SC-GW 16 may communicatetheir status to SC-GW 16 and SC-GW 16 (more particularly, ICM 17) maymonitor the interference amongst the SCBSs 11 and execute steps 401 thru420 as required.

The above described exemplary techniques may provide interferencecoordination using a centralized location point (for example, SC-GW). Bydetermining and providing the SCBSs with, for example, the PRB powerallocation and hopping sequence, the SC-GW may offload the processingrequired for interference coordination from the SCBSs.

FIG. 5 is an exemplary overview of the interference coordinationtechniques disclosed herein. In S501, SC-GW 16 (and more particularly,ICM 17) may receive uplink measurements and neighboring cell informationfrom SCBSs 11 connected to SC-GW 16. For example, if SCBSs B1, B2, B3,and B4 are connected to SC-GW 16, the ICM 17 may receive from the ICA 15of these SCBSs, uplink measurements and neighboring cell informationlike in S403 of FIG. 4B. The uplink measurements transmitted by each ofthe SCBSs may include: (a) uplink received co-channel & adjacent channelinterference power measured for the whole uplink system bandwidth of theSCBS; (b) minimum and maximum RSRP values reported by the UEs attachedto the SCBS; and (c) average uplink power allocation over the uplinksystem bandwidth. As discussed with respect to S403 in FIG. 4B, theuplink interference power and uplink power allocation may be specifiedby the SCBS for each of the SCBS's PRBs.

In S502, ICM 17 may form ICGs based on the information received in S501.For example, ICM 17 may retrieve from management application 301, one ormore ICG configuration parameters specified in S401 of FIG. 4A and theparameters specified in S402 of FIG. 4A. By utilizing these retrievedparameters, ICM 17 may form one or more ICGs, each of which may includea victim SCBS and one or more SCBSs interfering with the victim SCBS.For example, as discussed above with reference to FIGS. 4A-4F, an ICGmay be formed with B1 as the victim SCBS and B2, B3, and B4 as theinterfering SCBSs. To form the ICG, ICM 17 may execute, for example,S404 thru S411 of FIG. 4B-4C. For each ICG, ICM 17 may also determine aCRP that consists of one or more PRBs that are common across all themembers of that ICG.

In S503, ICM 17 may determine adjustments necessary to minimizeinter-cell interference in the different ICGs formed in S502. Forexample, ICM 17 may execute S413 thru S419 of FIGS. 4E and 4F todetermine uplink power allocation adjustments for interfering SCBSs.Additionally, as discussed in S419, ICM 17 may determine a hoppingsequence of non-overlapping PRBs for SCBSs of an ICG so that at a giventime each SCBS that is a member of a given ICG may not utilize the samePRBs for communication with their respective UEs.

In S504, ICM 14 may communicate the adjustments determined in S503 tothe various SCBSs by specifying the adjustments in the RAI of the SCBSs.As discussed in S420 of FIG. 4F, the transmission of the RAI may occurat predetermine intervals that may coincide with the hopping sequencedetermined in S503.

While exemplary machine algorithms have been described with reference toFIGS. 4A-4F and 5, it will be understood that certain exemplaryembodiments may change the order of steps in the machine algorithms ormay even eliminate or modify certain steps, or include additional ordifferent steps. For example, in FIGS. 4A-4F, S401 and S402 may beexecuted in ICM 17 after or in parallel with S403. Moreover, thedifferent components of SCBS 11 and SC-GW 16 may be embodied in hardwareor software or a combination of both. The hardware may include ageneral-purpose computer having a central processing unit (CPU) andmemory/storage devices that store data and various programs such as anoperating system and one or more application programs. Furthermore, eachof the steps in the machine algorithms described in FIGS. 4A-4F and 5may be embodied as computer-readable instructions or code and stored ina non-transitory computer-readable storage medium for execution by acomputer.

Other embodiments of the present disclosure will be apparent to thoseskilled in the art from consideration of the specification and practiceof the embodiments disclosed herein. It is intended that thespecification and examples be considered as exemplary only, with a truescope and spirit of the disclosure being indicated by the followingclaims.

What is claimed is:
 1. A processor-implemented inter-cell interferencecoordination method, comprising: forming, via one or more hardwareprocessors, a common resource pool of physical resource blocks that arecommon across an uplink bandwidth of member base stations of aninterference control group, wherein the member base stations aresmall-cell base stations configured to perform interferencecoordination; identifying, via the one or more hardware processors, thatone of the member base stations of the interference control group is aninterferer base station to a victim base station; determining, via theone or more hardware processor, after identifying the interferer basestation and the victim base station, an individual physical resourceblock from the common resource pool based on: an uplink interference,having power greater than a first threshold based on interferencecoordination group configuration parameters, experienced by the victimbase station for the individual resource block, and the interferer basestation having an allocated uplink power for the individual physicalresource block that is greater than a second threshold based oninterference coordination parameters; and reducing, via the one or morehardware processors, the allocated uplink power of the interferer basestation for the determined individual resource block by sending to theinterferer base station resource allocation information indicating thatthe allocated uplink power for the identified individual resource blockis reduced by a predetermined factor.
 2. The method of claim 1, whereinthe first threshold and the second threshold are based on small-cellgateway operator input.
 3. The method of claim 1, wherein the step ofdetermining the individual physical resource block from the commonresource pool is performed for each physical resource block of thecommon resource pool.
 4. The method of claim 1, wherein the resourceallocation information is broadcast at predetermined intervals.
 5. Themethod of claim 4, further comprising: reassigning a physical resourceblock to one of the member base stations between adjacent broadcasts. 6.A inter-cell interference coordination system comprising: one or morehardware processors; and a non-transitory computer-readable mediumstoring instructions that, when executed by the one or more hardwareprocessors, cause the one or more hardware processors to performoperations comprising: forming, via one or more hardware processors, acommon resource pool of physical resource blocks that are common acrossan uplink bandwidth of member base stations of an interference controlgroup, wherein the member base stations are small-cell base stationsconfigured to perform interference coordination; identifying, via theone or more hardware processors, that one of the member base stations ofthe interference control group is an interferer base station to a victimbase station; determining, via the one or more hardware processor, afteridentifying the interferer base station and the victim base station, anindividual physical resource block from the common resource pool basedon: an uplink interference, having power greater than a first thresholdbased on interference coordination group configuration parameters,experienced by the victim base station for the individual resourceblock, and the interferer base station having an allocated uplink powerfor the individual physical resource block that is greater than a secondthreshold based on interference coordination parameters; and reducing,via the one or more hardware processors, the allocated uplink power ofthe interferer base station for the determined individual resource blockby sending to the interferer base station resource allocationinformation indicating that the allocated uplink power for theidentified individual resource block is reduced by a predeterminedfactor.
 7. The system of claim 6, wherein the first threshold and thesecond threshold are based on small-cell gateway operator input.
 8. Thesystem of claim 6, wherein the step of determining the individualphysical resource block from the common resource pool is performed foreach physical resource block of the common resource pool.
 9. The systemof claim 6, wherein the resource allocation information is broadcast atpredetermined intervals.
 10. A non-transitory computer-readable mediumstoring instructions, wherein upon execution of the instructions by oneor more hardware processors, the hardware processors perform operationscomprising: forming, via one or more hardware processors, a commonresource pool of physical resource blocks that are common across anuplink bandwidth of member base stations of an interference controlgroup, wherein the member base stations are small-cell base stationsconfigured to perform interference coordination; identifying, via theone or more hardware processors, that one of the member base stations ofthe interference control group is an interferer base station to a victimbase station; determining, via the one or more hardware processor, afteridentifying the interferer base station and the victim base station, anindividual physical resource block from the common resource pool basedon: an uplink interference, having power greater than a first thresholdbased on interference coordination group configuration parameters,experienced by the victim base station for the individual resourceblock, and the interferer base station having an allocated uplink powerfor the individual physical resource block that is greater than a secondthreshold based on interference coordination parameters; and reducing,via the one or more hardware processors, the allocated uplink power ofthe interferer base station for the determined individual resource blockby sending to the interferer base station resource allocationinformation indicating that the allocated uplink power for theidentified individual resource block is reduced by a predeterminedfactor.
 11. The computer-readable medium of claim 10, wherein the firstthreshold and the second threshold are based on small-cell gatewayoperator input.
 12. The computer-readable medium of claim 10, whereinthe step of determining the individual physical resource block from thecommon resource pool is performed for each physical resource block ofthe common resource pool.
 13. The computer-readable medium of claim 10,wherein the resource allocation information is broadcast atpredetermined intervals.
 14. The computer-readable medium of claim 13,further comprising: reassigning a physical resource block to one of themember base stations between adjacent broadcasts.